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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Citrus and Other Subtropical Products Research » Research » Publications at this Location » Publication #332978

Research Project: Alternatives to Methyl Bromide Soil Fumigation for Vegetable and Floriculture Production

Location: Citrus and Other Subtropical Products Research

Title: Dominus: Nematode and pathogen control and improved weed control with fomesafen

Author
item Rosskopf, Erin
item Hong, Jason
item Burelle, Nancy
item Booker, Bradley - Pacific Ag Research, Inc
item Sances, Frank - Pacific Ag Research, Inc

Submitted to: Proceedings of Methyl Bromide Alternatives Conference
Publication Type: Proceedings
Publication Acceptance Date: 9/1/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary: Few new chemical fumigants have been developed in recent years. One of the exceptions is a biofumigant with the active ingredient allylisothiocyanate (AITC), registered as the commercial product Dominus® (Isagro, USA). Excellent control of fungal plant pathogens and nematodes has been achieved with this material in the field, but weed control has been variable. Weed control with laboratory-grade AITC requires a minimum application rate of 750 kg/ha, nearly twice the labeled rate of the registered product, and more is required for control of purple nutsedge. An experiment was conducted in which AITC was compared to the application of a combination of organic acids with and without a companion herbicide. Both tomatoes and peppers were included in the trial. Plant diseases, parasitic nematodes, and weed populations were monitored through the study. In the tomato trial, the soil treatments did not have an impact on weeds, but in the pepper crop, the herbicide had a significant impact on the nutsedge population. Tomato disease was most effectively controlled using the AITC product and root-knot nematodes were also most effectively controlled with this biofumigant.

Technical Abstract: Few new chemical fumigants have been developed in recent years. One of the exceptions is a biofumigant with the active ingredient allylisothiocyanate (AITC), registered as the commercial product Dominus® (Isagro, USA). Excellent control of fungal plant pathogens and nematodes has been achieved with this material in the field, but weed control has been variable (Rosskopf, unpublished). Weed control with laboratory-grade AITC requires a minimum application rate of 750 kg/ha, nearly twice the labeled rate of the registered product, and more is required for control of purple nutsedge . A factorial experiment was established comparing Dominus (30 gal/A) and an experimental organic acid treatment (SPK; 1714 gal/A) drip applied under totally impermeable film (TIF), with or without the herbicide Reflex (ai fomesafen) applied at 1 pint/A in 30 gal/A with two Teejet VS11002 flat fan nozzles at 30 psi spaced 12 inches apart prior to plastic application. Each plot was split to accommodate planting of tomato and pepper. Soil samples were taken prior to application to determine baseline parasitic and non-parasitic nematode populations. Soil samples were again collected to determine post-treatment nematode community changes. In-field disease ratings were performed throughout the season beginning with seedling damping off and continued through root condition ratings following the final harvest. Weed emergence data was taken from the total length of each replicated plot. After the final harvest, plants were removed from the soil and plant growth measurements, including top weight, root weight, and stem caliper at crown were recorded. The roots were rated for galling and root condition. At the end of the season, nematodes were extracted from plant root tissue, counted, and identified. Plots were harvested twice and yield recorded based on fruit size. In the tomato trial, there was no significant impact of either soil treatment (p=0.5886) nor herbicide (p=0.0945) on nutsedge, but in the pepper trial, herbicide application resulted in a significant decrease in nutsedge (p=0.0036). Total combined weed counts through the plastic and in planting holes from pepper and tomato combined were significantly decreased by the herbicide application (p=0.0053). Tomato bacterial wilt, caused by Ralstonia solanacearum, resulting in plant mortality, was significantly lower in Dominus-treated plots than in other soil treatments (p=0.0004). Populations of root-knot nematode were effectively controlled using Dominus (p=0.0055) when compared to an experimental material and to the untreated check. Fruit yield, from both tomato and pepper, was greatest (p<0.05) with Dominus, followed by the experimental material SPK, and finally the untreated check.